BMI Course Over 10 Years After Bariatric Surgery and Biopsychosocial Complexity Assessed with the INTERMED: a Retrospective Study

While bariatric surgery is an effective therapy for patients with severe obesity, not all patients benefit equally. An explanation might be that psychosocial risk factors hamper outcome. The study aimed to evaluate if biopsychosocial case complexity predicts evolution of BMI over 10 years after bariatric surgery. Charts of patients (N = 236) of the Cohort of Obesity Lausanne (COOL) were retrospectively reviewed and rated with the INTERMED, a reliable and validated instrument, which assesses biopsychosocial case complexity and has been proven to predict outcome of medical treatments in different patient populations. The sample was stratified into BMI quartiles, computed from the patients’ baseline BMI. For each quartile, BMI evolution was analyzed using individual growth curve analysis. Growth curve analyses showed that in quartiles 1, 2, and 3, none of the INTERMED domain scores significantly predicted the BMI evolution after surgery. However, in the fourth quartile—including patients with the highest pre-surgical BMI—the social domain score of the INTERMED significantly predicted BMI evolution: patients with more social complexity showed higher increase in BMI. Effectiveness of interventions targeted at social complexity, especially when patients suffer from severe obesity, may therefore be evaluated in future studies.